You'll need some way to get the audio into and out of your computer, beyond the low-quality built-in jack that it likely has. You'll also need more than two channels in-and-out at a time. Make sure you get one that is compatible with your present hardware/software system. I wrote a long guide to the many interfaces that are available:http://www.silentway.com/interfaces

Remember that the manufacturers are out to sell you stuff with promises of an easy learning curve. Be skeptical of their claims, and plan for some study. Nothing comes easy, but at least it's a good deal cheaper than it was 5-10 years ago...

I've never used the Delta 1010LT so I can't offer first-hand advice. It's not covered in my Guide because it is a PCI card. My list only covers FireWire and USB interfaces, for a few reasons (see the guide for why). One reason I've chosen not to spotlight PCI cards is that they have compatiblility issues, and the Delta 1010LT is a good example. Acccording to M-Audio,

The slightly older version of the Dual G5 1.8 GHz as well as the previous version of the Dual 2.0 GHz, which Apple advertises as “PCI-X” and not “PCI,” and which are also different from the newer model in that they have eight RAM slots instead of only four, ARE compatible and work perfectly well with M-Audio Delta Series PCI card. Please verify if you have one of these models before purchasing a PCI audio card.

Single Processor G5’s as well as Dual Processor G5’s with PCI-X and 8 RAM slots are NOT affected and work perfectly fine with M-Audio’s Delta Series of products.

M-Audio has worked closely with Apple to determine the source of this problem and it has been found to be the interaction of the host PCI controller (Apple's part named "K2") and the Delta PCI card.

The incompatibility manifests itself as noise in the signal, sample dropouts, and possibly no audio output at all.